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. Author manuscript; available in PMC: 2018 Oct 1.
Published in final edited form as: IEEE Trans Biomed Circuits Syst. 2017 Jul 20;11(5):1041–1052. doi: 10.1109/TBCAS.2017.2712566

Fig. 7.

Fig. 7

Measurements of input-referred thermal noise from 10 to 200 kHz for serial input resistances ranging from 0.1 Ω to 1 k ω are shown along with theoretical source resistor noise, amplifier voltage noise, and total input-referred noise for the custom MPI preamplifier alone and the preamplifier with transformer coupling. The measured noise-spectral density was frequency-independent in this bandwidth. Total input-referred noise measurements for varying resistor values correspond well with theory.